At first glance, Sunday’s Non Sequitur comic strip just showed bears dressed up like Leonardo da Vinci. The syndicated strip opens with Bear-Vinci holding a picture of a Virtruvian Bear. It ends with the ursine artist painting of Mona Lisa, who is also, you guessed it, a bear. They’re all characters in the “Bearaissance,” and the format invites readers to color in the drawings.

But much like da Vinci himself, Wiley Miller – whose work often tackles politics and has occasionally drawn controversy – could not resist inserting a secret message into his latest work. Hidden at the bottom right corner of the second panel, beneath a drawing of the Italian inventor’s flying machine, a semi-legible scribble appeared to read, “Go (expletive) yourself Trump.”

Miller has since apologized, saying he never intended for the public to see the statement. On Monday, multiple newspapers said they dropped the comic, including the Dallas Morning News, Columbia Dispatch, the Richmond Times-Dispatch and The Spokesman-Review.

“If one of our reporters or editors or illustrators were to purposely go around our editing processes in order to do something like this, they’d be fired immediately,” said Spokesman-Review editor Rob Curley. “That same standard absolutely has to apply in this situation.

“We’re not just apologetic that it appeared in our newspaper, we’re angry about it.”

According to the comic strip’s publisher, Andrews McMeel Universal, Non Sequitur goes out to more than 700 newspapers.

The Kansas City-based syndicate apologized for the vulgar language in a statement Monday.

“We are sorry we missed the language in our editing process,” the company said. “If we had discovered it, we would not have distributed the cartoon without it being removed. We apologize to ‘Non Sequitur’s’ clients and readers for our oversight.”

Many newspapers pre-print their Sunday comics sections – including The Spokesman-Review – meaning the Non Sequitur strip will appear in this coming week’s Sunday comics section because it already has been printed. As at most newspapers across the nation, the Sunday comics that appear in The Spokesman-Review are sent directly to the newspaper’s printing and production facility, where they are typically printed two weeks before they are delivered to subscribers.

“There are so many moving parts that you worry about when you publish a newspaper, that you don’t even think about the Sunday comics,” Curley said. “The newsroom doesn’t even see them before they run. You just trust that they’re fine. Well, that trust has been violated in regard to Non Sequitur.”

Because of other logistics issues, the Non Sequitur daily strip also will appear in The Spokesman-Review’s weekday papers until later in the week, when the strip will be replaced, Curley said.

The artist, who frequently criticizes President Trump on his Twitter feed, says he forgot all about the scribbled profanity until Sunday.

“When I opened the paper Sunday morning and read my cartoon, I didn’t think anything of it, as I didn’t notice the scribbling that has now caught fire,” Miller said in a statement released by the syndicate, noting that the scribble had been done several weeks ago at a time when he was frustrated by a White House action and forgot to remove it.

“It was not intended for public consumption, and I meant to white it out before submitting it, but forgot to. Had I intended to make a statement to be understood by the readers, I would have done so in a more subtle, sophisticated manner,” he said.

But on Sunday, he still teased the “Easter egg” in the “Non Sequitur” comic on Twitter, inviting people to look for a message.

Miller’s comics often carry a political message. A July 2016 comic depicted a character wearing KKK robes emblazoned with the message “I’m with Trump.”

Non Sequitur won the National Cartoonists Society’s Reuben Award for Outstanding Cartoonist of the Year in 2014. Launched in 1992, the comic has gone through several iterations since.

“I developed the strip to go into any direction my creativity would take me,” he told the Post in a 2014 interview. “It’s very open-ended. It’s like creating a new strip all the time.”

“I’m always trying to push things,” when it came to his art form, he said. “I haven’t had to apologize yet.”

Miller has faced controversy before for his work. In 2010, some newspapers decided not to run one of his cartoons depicting Mohammad, the founder of Islam who is seen as a prophet and holy figure by members of the religion.

“All I can do is surmise that the irony of their being afraid to run a cartoon that satirizes media’s knee-jerk reaction to anything involving Islam bounced right of their foreheads. So what they’ve actually accomplished is, sadly, to validate the point,” he told the Washington Post at the time.

On Monday, however, Miller was more apologetic. “In all that time, I have never done anything like this, nor do I intend to do so in the future,” he said.

His apology did not sway Dallas Morning News editor Mike Wilson, who accused Miller of going “around his editors and even his own syndicate to publish something he must have known we wouldn’t accept.

“We’ll have no trouble finding a better way to spend the $8,000 we would’ve paid for that strip,” Wilson said.